Guardians Tokens are a special currency using which legendary items can be crafted.
Along with embers, javelin parts or weapon parts, chimeric alloys and chimeric compounds, a guardian token can be offered in a Legionnaire's Tomb to craft legendary items. Depending upon the Legionnaire different types of items can be crafted.
During the Season of Icetide, one daily challenge rewarded and three weekly challenges rewarded a guardians token each. Using the token in Freeplay in Grandmaster 3 difficulty ensured the legendary item to have a power level of 80.
Since Update 1.7.0 all Weekly and monthly Path to Glory challenges, All Festive Daily and Weekly challenges reward 1 Guardians' Token when completed.